Planet hunting finds Ross exoplanet

Thursday 16th November 2017

Ross 128b with red dwarf parent star

An artist's impression shows temperate planet Ross 128 b, complete with its red dwarf parent star in the background. This planet is only 11 light-years from Earth, and was found by a team using ESO's unique planet-hunting HARPS.

A team working with ESO's High Accuracy Radial velocity Planet Searcher (HARPS) at the La Silla Observatory in Chile has found that the red dwarf star Ross 128 is orbited by a low-mass exoplanet every 9.9 days. This Earth-sized world is expected to be temperate, with a surface temperature that may also be close to that of the Earth. Ross 128 is the "quietest" nearby star to host such a temperate exoplanet.

"This discovery is based on more than a decade of HARPS intensive monitoring together with state-of-the-art data reduction and analysis techniques. Only HARPS has demonstrated such a precision and it remains the best planet hunter of its kind, 15 years after it began operations," explains Nicola Astudillo-Defru
(right ) Nicola Astudillo-Defru ( Geneva Observatory - University of Geneva, Switzerland), who co-authoredthe discovery paper.

Red dwarfs are some of the coolest, faintest—and most common—stars in the Universe. This makes them very good targets in the search for exoplanets and so they are increasingly being studied. In fact, lead author Xavier Bonfils (Institut de Planétologie et d'Astrophysique de Grenoble - Université Grenoble-Alpes/CNRS, Grenoble, France), named their HARPS programme The shortcut to happiness, as it is easier to detect small cool siblings of Earth around these stars, than around stars more similar to the Sun.

Many red dwarf stars, including Proxima Centauri, are subject to flares that occasionally bathe their orbiting planets in deadly ultraviolet and X-ray radiation. However, it seems that Ross 128 is a much quieter star, and so its planets may be the closest known comfortable abode for possible life. Read more